Bearing elements, bearing apparatuses including same, and related methods

ABSTRACT

Bearing apparatuses including contacting bearing surfaces comprising superhard materials are disclosed. In one embodiment, the present invention relates to bearings including polycrystalline diamond inserts or compacts defining a plurality of surfaces that move relative to one another and contact one another. For example, apparatuses may include radial bearings, or other bearings including arcuate bearing surfaces that more in relation to one another, without limitation. In one embodiment, a superhard bearing element may comprise a superhard table (e.g., polycrystalline diamond) forming an arcuate bearing surface. Further, such a superhard bearing element may comprise a chamfer formed about at least a portion of a periphery of the arcuate bearing surface. Bearing apparatuses including such bearing elements and various mechanical systems are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/540,059, filed Jul. 2, 2012, which is a continuation of U.S. patentapplication Ser. No. 11/465,010 filed Aug. 16, 2006, now U.S. Pat. No.8,210,747, which is a continuation-in-part of U.S. patent applicationSer. No. 11/212,232, filed Aug. 26, 2005, now U.S. Pat. No. 7,703,982,the disclosures of each which are incorporated, in their entireties, bythis reference.

BACKGROUND

Conventional bearing apparatuses including bearing surfaces that moverelative to one another are known in the art. For example, conventional,so-called “thrust bearings” and some embodiments of radial bearingsinclude bearing surfaces that at least partially contact and move orslide relative to one another. Such bearing surfaces may include asuperhard material for resisting wear during use of the bearing. In oneexample, diamond (e.g., polycrystalline diamond) may comprise at leastone or both of the bearing surfaces.

More particularly, one application for bearings is drilling equipmentutilized in the subterranean drilling arts. Particularly, drillingmotors and drill bits with moving members, such as roller cones havebeen utilized for drilling boreholes into a subterranean formation,especially for oil or gas exploration. In a typical downhole drillingmotor, the motor is suspended at the lower end of a string of drill pipecomprising a series of pipe sections connected together at joints andsupported from the surface. A rotary drill bit (e.g., a fixed cutterdrill bit, roller cone drill bit, a reamer, etc.) may be supported belowthe drilling motor (via pipe sections, drill collars, or otherstructural members as known in the art) or may be directly connected tothe downhole motor, if desired. Drilling fluid, which is commonly knownas drilling mud, is circulated through the pipe string and the motor togenerate torque within the motor for causing the rotary drill bit torotate. Then, the drilling fluid is returned to the surface through theannular space between the drilled borehole and the drill string and maycarry the cuttings of the subterranean formation to the surface.

Further, as known in the art, mechanical systems may include radialbearings. For example, conventional downhole drilling may employ radialbearings. In one embodiment, an inner and outer race are each providedwith a plurality of superhard bearing elements (e.g., polycrystallinediamond elements). The races are positioned adjacent one another so thatthe bearing surfaces of the bearing elements contact one another. As maybe appreciated, geometry and configuration of the bearing elements ofthe races may be an important factor influencing the performance andlife of such a bearing structure. Examples of conventional radialbearing apparatuses are disclosed by U.S. Pat. Nos. 4,662,348,4,729,440, 4,738,322, 4,756,631, and 4,764,036, the disclosure of eachof which is incorporated, in its entirety, by this reference.

Thus, it would be advantageous to provide improved bearing elements andbearing apparatuses including same.

SUMMARY

The present invention relates generally to bearing elements and bearingapparatuses including contacting bearing surfaces comprising superhardmaterials. In one embodiment, the present invention relates to bearingsincluding polycrystalline diamond inserts or compacts defining aplurality of surfaces that move relative to one another and contact oneanother. For example, the present invention relates to radial bearings,or other bearings including arcuate bearing surfaces that more inrelation to one another, without limitation.

In one embodiment, the present invention relates to bearings includingpolycrystalline diamond inserts or compacts defining a plurality ofsurfaces that move relative to one another and contact one another. Suchbearing apparatuses may encompass so-called thrust bearings, radialbearings, or other bearings including bearing surfaces that more inrelation to one another, without limitation.

One aspect of the instant disclosure relates to a bearing apparatus.Particularly, a bearing apparatus may comprise a rotor including atleast one bearing element mounted to the rotor and a stator including atleast one bearing element mounted to the stator. The at least onebearing element of the rotor may define a bearing surface and the atleast one bearing element of the stator may define another bearingsurface. Further, at least one compliant member may be positionedbetween at least one selected bearing element of the at least onebearing element mounted to the rotor and the at least one bearingelement mounted to the stator. The at least one compliant member may beconfigured to allow for a selected magnitude of variation in theorientation of a bearing surface of the at least one selected bearingelement. Various mechanical systems may include such a bearingapparatus.

One aspect of the present invention relates to bearing elements.Particularly, one aspect of the present invention relates to a superhardbearing element comprising a superhard table forming an arcuate bearingsurface. Further, such a superhard bearing element may comprise achamfer formed about at least a portion of a periphery of the arcuatebearing surface.

Another aspect of the instant disclosure relates to polycrystallinediamond bearing elements. Particularly, one aspect of the presentinvention relates to a polycrystalline diamond bearing elementcomprising a polycrystalline diamond table forming an arcuate bearingsurface. Further, such a polycrystalline diamond bearing element maycomprise a chamfer formed about at least a portion of a periphery of thearcuate bearing surface.

Another aspect of the present invention relates to bearing apparatuses.More specifically, a bearing apparatus according to the presentinvention may comprise an inner race and an outer race. In furtherdetail, the inner race may comprise a plurality of inner race superhardbearing elements, each comprising a superhard table, wherein at leastone of the plurality of inner race superhard elements includes an innerarcuate bearing surface and a chamfer formed about at least a portion ofa periphery of the inner arcuate bearing surface. In addition, the outerrace may comprise a plurality of outer race superhard bearing elementseach comprising a superhard table, wherein at least one of the pluralityof outer superhard elements includes an outer arcuate bearing surfaceand a chamfer formed about at least a portion of a periphery of theouter arcuate bearing surface. Various mechanical systems may includesuch a bearing apparatus. In one embodiment, a bearing apparatus may beconfigured as a radial bearing apparatus included within a rolling conedrill bit.

Features from any of the above mentioned embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the instant disclosure will become apparentto those of ordinary skill in the art through consideration of theensuing description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the subject matter of the instant disclosure, itsnature, and various advantages will be more apparent from the followingdetailed description and the accompanying drawings, which illustratevarious exemplary embodiments, are representations, and are notnecessarily drawn to scale, wherein:

FIG. 1 shows a perspective view of a stator according to the presentinvention;

FIG. 2 shows a top elevation view of the stator shown in FIG. 1;

FIG. 3 shows a side cross-sectional view of the stator shown in FIGS. 1and 2;

FIG. 4 shows a perspective view of a stator assembly including a statoras shown in FIGS. 1-3 and a plurality of bearing elements coupled to thestator;

FIG. 5 shows a perspective view of a bearing element including a tablebonded to a substrate;

FIG. 6 shows a partial, exploded, side cross-sectional assembly view ofthe stator assembly shown in FIG. 4;

FIG. 7 shows a perspective view of one embodiment of a compliant memberaccording to the present invention;

FIG. 8 shows a side cross-sectional view of the compliant member shownin FIG. 7;

FIG. 9 shows a partial, schematic, side cross-sectional view of abearing element and compliant member positioned generally within arecess of a stator;

FIG. 10 shows a partial, schematic, side cross-sectional view of thebearing element and compliant member shown in FIG. 9, wherein anorientation of a bearing surface of the bearing element varies withrespect to a desired orientation;

FIG. 11 shows a schematic view of a bearing element coupled to a statorby a plurality of biasing elements;

FIG. 12 shows a schematic view of a bearing element coupled to a statorby one biasing element;

FIG. 13 shows a partial, schematic, side cross-sectional view of abearing element coupled to a stator, wherein a washer spring ispositioned between the bearing element and the stator;

FIG. 14 shows a perspective view of a rotor assembly including a rotorand a rotor base;

FIG. 15 shows a perspective view of a bearing apparatus according to thepresent invention including a stator assembly and a rotor assembly;

FIG. 16 shows a partial, schematic view of a bearing apparatus, whereinrespective compliant members are positioned between respective bearingelements of a stator and a rotor;

FIG. 17 shows a schematic view of the bearing apparatus shown in FIG.16, wherein the rotor and stator are compressed toward one another;

FIG. 18 shows a schematic view of a bearing apparatus, wherein acompliant member is positioned between at least one bearing element of arotor or a stator;

FIG. 19 shows a schematic view of the bearing apparatus shown in FIG. 18wherein the rotor and the stator are compressed toward one another;

FIG. 20 shows a perspective view of an outer race including a pluralityof bearing elements coupled to the outer race;

FIG. 21 shows a perspective view of the bearing element shown in FIG.20;

FIG. 22 shows a partial, exploded, assembly view of the outer race shownin FIG. 20;

FIG. 23 shows a partial, side cross-sectional view of the outer raceshown in FIG. 22;

FIG. 24 shows a side cross-sectional view of a compliant member as shownin FIGS. 22 and 23;

FIG. 25 shows a perspective view of an inner race including a pluralityof bearing elements coupled to the inner race;

FIG. 26 shows a perspective view of the bearing element as shown in FIG.25;

FIG. 27 shows a partial, exploded assembly view of the inner race shownin FIG. 25;

FIG. 28 shows a perspective view of a radial bearing assembly accordingto the present invention;

FIG. 29 shows a perspective view of a subterranean drilling systemincluding a thrust bearing apparatus according to the present invention;

FIG. 30 shows a perspective view of one embodiment of a bearing elementaccording to the present invention;

FIG. 31 shows a top elevation view of the bearing element shown in FIG.30;

FIG. 32 shows a perspective view of another embodiment of a bearingelement according to the present invention;

FIG. 33 shows a top elevation view of the bearing element shown in FIG.32;

FIG. 34 shows a perspective view of a further embodiment of a bearingelement according to the present invention;

FIG. 35 shows a top elevation view of the bearing element shown in FIG.34;

FIG. 36 shows a perspective view of yet an additional embodiment of abearing element according to the present invention;

FIG. 37 shows a top elevation view of the bearing element shown in FIG.36;

FIG. 38 shows a schematic diagram depicting one embodiment of a methodfor forming a bearing element according to the present invention;

FIG. 39 shows a schematic diagram depicting another embodiment of amethod for forming a bearing element according to the present invention;

FIG. 40 shows a perspective view of a bearing element according to thepresent invention at an intermediate stage during manufacturing;

FIG. 41 shows a perspective view of a bearing element according to thepresent invention at an intermediate stage of manufacturing;

FIG. 42A shows a side cross-sectional view of the bearing element shownin FIG. 41;

FIG. 42B shows a side cross-sectional view of a bearing elementincluding a radius formed about at least a portion of a periphery of abearing surface;

FIG. 43 shows a partial, exploded perspective view of an outer race anda bearing element at an intermediate stage of manufacture;

FIG. 44 shows a perspective view of an outer race including a pluralityof bearing elements according to the present invention coupled to theouter race;

FIG. 45 shows a partial, exploded perspective view of an inner race anda bearing element at an intermediate stage of manufacture;

FIG. 46 shows a perspective view of an inner race including a pluralityof bearing elements according to the present invention coupled to theinner race;

FIG. 47 shows a perspective view of a radial bearing assembly accordingto the present invention; and

FIG. 48 shows a perspective view of a subterranean drilling systemincluding a bearing apparatus according to the present invention.

DETAILED DESCRIPTION

The present invention relates generally to bearing apparatuses includingbearing surfaces comprising superhard materials. “Superhard,” as usedherein, refers to any material having a hardness that is at least equalto or exceeds a hardness of tungsten carbide (e.g., polycrystallinediamond, boron nitride, silicon carbide, mixtures of the foregoing, orany suitable material). For example, a polycrystalline diamond compact(PDC) is normally fabricated by placing a cemented carbide substrateinto a container or cartridge with a layer of diamond crystals or grainspositioned adjacent one surface of a substrate. A number of suchcartridges may be typically loaded into an ultra-high pressure press.The substrates and adjacent diamond crystal layers are then sinteredunder ultra-high temperature and ultra-high pressure (“HPHT”)conditions. The ultra-high pressure and ultra-high temperatureconditions cause the diamond crystals or grains to bond to one anotherto form polycrystalline diamond. In addition, as known in the art, acatalyst may be employed for facilitating formation of polycrystallinediamond. In one example, a so-called “solvent catalyst” may be employedfor facilitating the formation of polycrystalline diamond. For example,cobalt, nickel, and iron are among examples of solvent catalysts forforming polycrystalline diamond. In one configuration, during sintering,solvent catalyst comprising the substrate body (e.g., cobalt from acobalt-cemented tungsten carbide substrate) becomes liquid and sweepsfrom the region adjacent to the diamond powder and into the diamondgrains. Of course, a solvent catalyst may be mixed with the diamondpowder prior to sintering, if desired. Thus, diamond grains becomemutually bonded to form a polycrystalline diamond table upon thesubstrate. A conventional process for forming polycrystalline diamondcutters is disclosed in U.S. Pat. No. 3,745,623 to Wentorf, Jr. et al.,the disclosure of which is incorporated, in its entirety, by thisreference. The solvent catalyst may remain in the polycrystallinediamond layer within the interstitial pores between the diamond grainsor may be at least partially removed by leaching (i.e., exposing atleast a portion of the diamond table to an acid) or by any suitablemethod. Optionally, another material may replace the solvent catalystthat has been at least partially removed from the polycrystallinediamond. In another embodiment, optionally, polycrystalline diamond mayinclude nanodiamond (i.e., ultra-dispersed diamond), if desired. Inanother example, a silicon carbide and diamond composite material asdisclosed in U.S. Pat. No. 7,060,641, the disclosure of which isincorporated herein, in its entirety, by this reference may comprise abearing surface.

One aspect of the present invention relates generally to bearingapparatuses including a rotor and a stator wherein the rotor includes aplurality of bearing elements defining a bearing surface and the statorincludes a plurality of bearing elements defining another bearingsurface. Such bearing elements may comprise a superhard material, suchas, for example, polycrystalline diamond. According to one aspect of thepresent invention, a compliant member may be positioned between at leastone bearing element of the bearing apparatus. Such a compliant membermay allow for variation in the orientation, position, or position andorientation of at least one of the bearing elements of the bearingapparatus. In addition, such a configuration may promote continuedcontact between the bearing surface of the rotor and the bearing surfaceof the stator. In addition, as described in greater detail below, such acompliant member may provide compressive contact between the bearingsurface of the stator and the bearing surface of the rotornotwithstanding variations in the orientation, position, or bothorientation and position of the bearing elements.

In one embodiment contemplated by the present invention, a stator mayinclude at least one bearing element wherein a compliant member ispositioned between the at least one bearing element mounted to thestator. For example, FIG. 1 shows a perspective view of stator 10comprising body 12, which defines a plurality of recesses 14 eachconfigured for accepting a bearing element positioned generally therein.As shown in FIG. 1, body 12 of stator 10 may be configured in agenerally ring-shaped or toroid-shaped configuration and may define anaperture 16 which is generally centered about longitudinal axis 11.

As shown in FIG. 2, which shows a top elevation view of stator 10, body12 of stator 10 may form a substantially cylindrical toroid-shapedgeometry and, accordingly, aperture 16 may be substantially cylindrical.Further, recesses 15 may each be positioned at substantially the sameradius (i.e., upon a common bolt circle) and may be substantiallyequally circumferentially spaced with respect to one another in relationto longitudinal axis 11. In addition, FIG. 2 shows that each of recesses14 may include a counterbore feature 15. A counterbore feature 15 mayembody, generally, any recess or depression that enlarges an opening ofa recesses 14. Explaining further, counterbore feature 15 may comprise arelatively shallow recess having a larger cross-sectional size than across-sectional size of the recess 14 with which it is aligned. As shownin FIG. 2, counterbore feature 15 may be a substantially cylindricaldepression which is substantially centered with respect to recess 14.FIG. 3 shows a side cross-sectional view of stator 10 taken through tworecesses 14. As shown in FIG. 3, recesses 14 may extend at leastpartially through body 12 of stator 10. Also, FIG. 3 shows thatcounterbore features 15 may form a ledge or lip within each of recesses14. Counterbore features 15 and corresponding ledges within recesses 14may facilitate mounting of bearing elements within recesses 14.

Generally, one aspect of the present invention relates to positioning acompliant member between a bearing element mounted to either a rotor ora stator of a bearing apparatus. Thus, a compliant member may bepositioned between a bearing element and a stator 10 as shown in FIGS.1-3. For example, FIG. 4 shows a perspective view of stator assembly 50including a plurality of bearing elements 20, wherein each bearingelement 20 is positioned within a respective recess 14 of the pluralityof recesses 14 formed in the body 12 of stator 10. More particularly, acompliant member 30 may be positioned between each of bearing elements20 and each of recesses 14, respectively. Body 12 may be configured forsupporting each of bearing elements 20 and may comprise a relativelyrigid material having a relatively high yield strength and modulus ofelasticity. For example, body 12 of stator 10 may comprise a highstrength steel (e.g., 4140 AISI steel, or other high strength steel asknown in the art).

FIG. 5 shows a perspective view of bearing element 20 including a table22 bonded to a substrate 24. Table 22, as known in the art, may comprisea superhard material (e.g., polycrystalline diamond, cubic boronnitride, silicon carbide, or any other superhard material as known inthe art). Such a configuration may provide a bearing surface 28 that isrelatively wear resistant. Furthermore, table 22 includes a bearingsurface 28 and may optionally include a chamfer 27. Bearing surface 28may be substantially planar and may be configured to contact anotherbearing element (e.g., a bearing element coupled to a rotor) includinganother bearing surface that corresponds to bearing surface 28. In oneembodiment, bearing element 20 may comprise a polycrystalline diamondcompact (“PDC”), as known in the art. In such a configuration, substrate24 may comprise a cobalt sintered tungsten carbide and table 22 maycomprise polycrystalline diamond. As known in the art, polycrystallinediamond may include a catalyst (e.g., cobalt, nickel, iron, or any othercatalyst as known in the art) to facilitate formation of polycrystallinediamond. Optionally, at least a portion of a catalyst within table 22may be removed (e.g., by acid leaching or as otherwise known in theart). As shown in FIG. 5, bearing element 20 may be substantiallycylindrical.

As shown in FIG. 6, compliant member 30 may include recess 32 configuredfor accepting a bearing element 20. Further, compliant member 30 may beconfigured to generally correspond to the shape of recess 14 formed inbody 12 of stator 10. Thus, compliant member 30 may be configured tosurround at least a portion of a periphery (e.g., a circumference) ofbearing element 20 and may provide a desired level of compliance betweensuch a bearing element 20 and recess 14. Accordingly, compliant member30 may comprise a material having a relatively moderate modulus ofelasticity (e.g., between about 5,000 ksi and about 30,000 ksi). Forexample, compliant member may comprise materials including, but notlimited to, aluminum, copper, titanium, brass, or bronze. Such aconfiguration may allow for variation in the position, orientation, orposition and orientation of bearing element 20 when it is positionedgenerally within a recess 14. Explaining further, a force or a momentapplied to bearing element 20 may cause elastic deformation of compliantmember 30.

FIG. 7 shows a perspective view of one embodiment of a compliant member.More particularly, FIG. 7 shows a compliant member 30 which is generallytubular and substantially cylindrical. Further, compliant member 30defines a generally cylindrical recess 32 at its closed end. Further,FIG. 8 shows a side cross-sectional view of the compliant member 30shown in FIG. 7. As shown in FIGS. 7 and 8, compliant member 30 includesa flange 36, an outer lip 34, and an inner lip 38. Flange 36 may beconfigured to fit within (i.e., with clearance between) counterborefeature 15 of recess 14 formed in stator 10. Optionally, outer lip 34may be configured for at least partially interfering with the bore ofrecess 14, if desired, which may facilitate retention of compliantmember 30 within recess 14. Optionally, inner lip 38 may be configuredto interfere with an outer periphery of a bearing element 20. Such aconfiguration may facilitate retention of a bearing element 20 within acompliant member 30 positioned within a recess 14 of stator 10 or mayseparate a lower surface of bearing element 20 from a lower surface ofcompliant member 30, as discussed below. Compliant member 30 may beconfigured to exhibit a selected level of elastic deformation forcompliance, which may allow a bearing element associated therewith toexhibit variation in its orientation and/or position.

FIG. 9 shows a partial, schematic, side cross-sectional view of stator10, illustrating a bearing element 20 and a compliant member 30positioned within recess 14. Axis Z is shown, however, the cross sectionof bearing element 20, compliant member 30, and recess 14 shown in FIG.9 is generic, which means that it may embody any selected plane takenthrough such elements. As shown in FIG. 9, flange 36 may be positionedgenerally within counterbore feature 15 (outer lip 34 and inner lip 38,as shown in FIGS. 7 and 8, are omitted for clarity). It may beappreciated that compliant member 30 may fit within recess 14 of stator10 with clearance. In addition, optionally, bearing element 20 may fitwithin compliant member with clearance. More particularly, as shown inFIG. 9, gaps (labeled “g”) of between about 0.002 inches and 0.005inches may exist between a peripheral side surface of the compliantmember 30 and the recess 14. Further, as shown in FIG. 9, a gap (labeled“g”) of between about 0.002 inches and 0.005 inches may exist between alower surface of the compliant member 30 and a lower surface defining aportion of recess 14. As a further variation, a lower surface of bearingelement 20 may be offset from a lower surface of compliant member 30(e.g., by a gap “g”), if desired. Thus, as may be appreciated, compliantmember 30, recess 14, and bearing element 20 may allow for variation inthe position of bearing element 20 along a lateral direction (i.e.,substantially perpendicular to longitudinal direction Z, which may beeither a circumferential direction, a radial direction, or both) andalong a longitudinal direction Z. In one embodiment, compliant member 30may support bearing element 20 within recess 14, wherein recess 14 and aperiphery of compliant member 30 are substantially separated. Of course,the relative size of gaps g may be adjusted to provide a selectivemagnitude of movement or play (and corresponding flexibility behavior orspring constant) to a bearing element 20. Thus, it may be appreciatedthat bearing element 20 may be displaced circumferentially (i.e., aboutlongitudinal axis 11), radially (outwardly or inwardly with respect tolongitudinal axis 11), or both, depending on the forces applied tobearing element 20. Similarly, bearing element 20 may be displacedupwardly along axis Z or downwardly along axis Z depending on the forceapplied to bearing element 20 in a longitudinal direction. Of course,such displacements may cause an orientation of bearing surfaces 28 ofbearing elements 20 to vary.

Explaining further, compliant member 30 may be configured to allow aselected level of variation in the orientation of bearing surface 28. Asshown in FIG. 10, angle θ may be formed between a reference plane P andbearing surface 28. Although bearing surface 28 is depicted in FIG. 10as being substantially planar, the present invention contemplates thatbearing surface 28 may be arcuate or may be configured as otherwiseknown in the art. Thus, if bearing surface 28 is arcuate, angle θ may bemeasured between a selected position (e.g., a line) of the arcuatebearing surface and reference plane P. In one embodiment, angle θ mayvary (i.e., compliant member 30 may be structured to allow angle θ tovary) within about .+−.2° of a desired orientation (e.g., referenceplane P). More specifically, variation of angle θ within about .+−.1° ofa desired orientation (e.g., reference plane P) may be ample for mostapplications. Within such orientation variation, compliant member 30 maybe configured to exhibit elastic deformation. Such a configuration mayallow for an orientation of bearing element 20 (e.g., bearing surface28) to change during the operation of a bearing apparatus. The crosssection shown in FIG. 10 is merely schematic and may embody any selectedcross section (of the components) taken in any selected direction,without limitation. Accordingly, orientation of bearing surface 28 mayvary (e.g., tip or tilt) in any direction or manner. Thus, it may beappreciated that during operation of a bearing apparatus, a force Fapplied to a portion of bearing element 20, as shown in FIG. 10, maycause the bearing surface 28 of bearing element 20 to change itsorientation. Such a force F may be generated via contact between bearingelements coupled to a stator and rotor, as known in the art. The presentinvention contemplates that a compliant member positioned between atleast one bearing element of either a stator or a rotor or both a statorand a rotor may be advantageous to allow for variation in anorientation, position, or orientation and position of such at least onebearing element.

More conceptually, the present invention contemplates that at least onebiasing element positioned between a bearing element and a stator (or arotor). For example, FIG. 11 shows a schematic view of a bearing element20 coupled to the body 12 of stator 10 by biasing elements K_(r) andK_(z). Thus, it may be appreciated that a spring constant or stiffnessmay be selected for each of biasing elements K_(r) and K_(z) to providea selected level of compliance in a longitudinal direction Z and alateral direction, respectively. In one embodiment, biasing elementK_(r) and biasing element K_(z) may function substantiallyindependently. For example, a compliant sleeve may be positioned aboutat least a portion of a side periphery 26 (e.g., an outer diameter orcircumference) to provide a biasing element between body 12 of stator 10and bearing element 20. Further, a disc-shaped biasing element K_(z)(e.g., a washer spring or other spring as known in the art) may bepositioned between a lower surface 23 of bearing element 20 and a body12 of stator 10. Thus, conceptually, radial compliance, circumferentialcompliance, and longitudinal compliance may be independent of oneanother. In other embodiments, radial compliance, circumferentialcompliance, and longitudinal compliance may be interdependent.

In another embodiment, a biasing element K may be positioned betweenbearing element 20 and body 12 of stator 10. Biasing element K may beconfigured to provide compliance with respect to a position, anorientation, or both in at least one direction or degree of freedom. Forexample, biasing element K may allow for variation in an orientation ofbearing surface 28 and, optionally, may allow for variation in alongitudinal position of bearing surface 28 of bearing element 20. Forexample, FIG. 13 shows a partial, schematic, side cross-sectional viewof a stator assembly 50 including a washer spring 70 (e.g., a wavespring washer, a curved spring washer, or a Belleville spring washer)positioned between a bearing element 20 and a recess 14 formed in thebody 12 of stator 10. As shown in FIG. 13, recess 14 may be larger thansubstrate 24 of bearing element 20. Thus, a gap “g” may be providedbetween a sidewall of substrate 24 and a sidewall of recess 14. Gap gmay be between about 0.002 inches and 0.005 inches, without limitation.Such a configuration may allow for bearing element 20 to be displacedgenerally within recess 14 (e.g., radially, circumferentially, orlongitudinally). Further, such configuration may allow for variation inthe orientation of bearing surface 28, as discussed above with respectto FIG. 10. Optionally, a fastening element 77 (e.g., a threadedfastener or other fastener as known in the art) may couple the substrate24 of bearing element 20 to stator 10 to prevent the bearing elementfrom being removed from recess 14. However, such a fastening element 77may be configured to allow for a selective range of movement (e.g.,longitudinal and orientation of the bearing surface 28) of the bearingelement 20 within recess 14 of stator 10 (i.e., against washer spring70). In addition, such a configuration may allow for the bearingelements of the rotor and the stator to be compressively forced againstone another, as discussed in further detail below. Also, it may beunderstood that such compressive force may be desirable for retainingbearing element 20 generally within recess 14 formed within the body 12of stator 10.

FIG. 14 shows a perspective view of rotor assembly 60 including bearingelements 80, rotor 90, and rotor base 100. As known in the art, rotor 90and rotor base may be substantially cylindrical and may be affixed toone another. As shown in FIG. 14, rotor 90 may comprise a generallyring-shaped body that may be coupled to rotor base 100. In addition,bearing elements 80 may be configured so that alignment and rotation ofrotor assembly 60 with stator assembly 50 results in at least onebearing surface 28 of a bearing element 20 being in substantiallyconstant contact with at least one respective bearing surface 88 ofbearing elements 80. Put another way, upon rotation of rotor assembly 60a bearing surface 88 of a bearing element 80 contacts acircumferentially adjacent bearing surface 28 of a bearing element 20prior to loss of contact with a circumferentially proceeding bearingsurface 28 of a bearing element 20. Of course, many embodiments relatingto the arrangement of bearing elements associated with a rotor andbearing elements associated with a stator are contemplated by thepresent invention and any configurations as known in the art may beemployed within a bearing apparatus according to the present invention.

From the foregoing description, it may be appreciated that a rotorassembly 60 and a stator assembly 50 may be used in combination with oneanother to form a bearing apparatus. For example, FIG. 15 shows aperspective view of a bearing apparatus 110 including stator assembly 50and rotor assembly 60. During use, rotor assembly 60 and stator assembly50 may be aligned with one another and the bearing surfaces 28 ofbearing elements 20 may be in contact with the bearing surfaces 88 ofbearing elements 80, respectively. Of course, rotor assembly 60 andstator assembly 50 may be affixed to a system to provide a thrustbearing structure. It should also be appreciated that the terms “rotor”and “stator” refer to rotating and stationary portions of a bearingapparatus, respectively, and, therefore, “rotor” and “stator” may referto identical components configured to rotate and remain stationary,respectively. It should be appreciated that rotor 90 may include atleast one compliant member positioned between at least one bearingelement 80 and the body defining rotor 90. Summarizing, at least one ofbearing elements 20 or bearing elements 80 may be coupled to stator 10or rotor 90, respectively, via a compliant member. In one embodiment, asdescribed above, each of the plurality of bearing elements 20 may becoupled to stator 10 via a respective compliant member. In anotherembodiment, each of bearing elements 80 may be coupled to rotor 90 by arespective compliant member.

FIG. 16 shows a schematic view of a bearing apparatus 110 including arotor 90 and a stator 10 wherein compliant members K_(u) and K_(l) arepositioned between the bearing elements 20, 80 of stator 10 and rotor90, respectively. As shown in FIG. 16, bearing surfaces 28, 88 mayinitially contact one another and may be positioned away from stator 10and rotor 90 by longitudinal distances Z₁ and Z₂. Although bearingelements 20, 80 are shown as being substantially identical in FIG. 16 itshould be understood that such a representation is merely illustrativeand not drawn to scale. Therefore, bearing elements 20, 80 may beconfigured as described above or as otherwise known in the art, withoutlimitation. FIG. 17 shows the bearing apparatus 110 as shown in FIG. 16,wherein a compressive force F is applied to stator 10 and rotor 90. Asshown in FIG. 17, compressive force F may cause bearing elements 20, 80to be positioned with respect to stator 10 and rotor 90 at respectivelongitudinal distances Z_(1c) and Z_(2c), wherein Z_(1c) is less than Z₁and Z_(2c) is less than Z₂. Accordingly, it may be appreciated thatcompliant members K_(u) and K_(l) are compressed by compressive force F.Of course, as shown in FIGS. 18 and 19, more generally, at least onecompliant member K may be positioned between at least one bearingelement 20, 80 of a stator 10 or rotor 90. Similar to theabove-described embodiment, a compressive force F may cause bearingelement 20, 80 to be positioned at respective longitudinal distances Z₁and Z_(1c), wherein Z_(1c) is less than Z₁, as shown in FIGS. 18 and 19.Such a compressive force F (FIGS. 17 and 19) may be referred to as a“preload” between the rotor and stator and may be applied by a clampingdevice or other device as known in the art, which maintains thecompressive force during relative rotation between stator 10 and rotor90. For example, in one embodiment, a clamping device may include atleast one rolling element configured to roll along a surface of at leastone of stator 10 and rotor 90 while providing a compressive forcetherebetween.

The present invention further contemplates that at least one compliantmember may be included within a radial bearing apparatus that includes afirst plurality of bearing elements collectively defining a firstbearing surface and a second plurality of bearing elements collectivelydefining a second bearing surface. For example, FIG. 20 shows aperspective view of an outer race 210 including a plurality of bearingelements 220. More specifically, outer race 210 may comprise a body 212defining a plurality of recesses 214 within which bearing elements 220may be positioned, respectively. Further, in the embodiment shown inFIG. 20, a compliant member 230 may be positioned between each of thebearing elements 220 and the recesses 214 of outer race 210. Also, FIG.21 shows a perspective view of bearing element 220, which may begenerally configured as described above with respect to bearing elements20 and 80. Thus, bearing element 220 includes a table 222 bonded to asubstrate 224 wherein table 222 defines a bearing surface 226. However,as shown in FIG. 21, bearing surface 226 may be substantially concave.In one embodiment, bearing surface 226 may comprise a portion of asubstantially cylindrical surface. In addition, bearing element 220 mayoptionally include substantially planar surfaces 228 and a chamfer 227.Also, substrate 224 may optionally include a chamfer 229, as shown atFIG. 21.

FIG. 22 shows a partial exploded assembly view of outer race 210including one bearing element 220 and its associated compliant member230. In further detail, FIG. 23 shows a partial, side cross-sectionalview of the partial assembly of outer race 210 shown in FIG. 22. Asshown in FIGS. 22 and 23, compliant member 230 may include a pluralityof apertures 240 formed therethrough. Such apertures 240 may beconfigured to provide a selected level of compliance to a bearingelement positioned therein. Apertures 240 are shown in FIGS. 24 and 25to be circumferentially spaced about the cylindrical sidewall ofcompliant member 230. However, the present invention contemplates otherembodiments for apertures 240. For instance, apertures 240 may be formedin a longitudinal direction about the circumference of the compliantmember to form a plurality of tines or prongs extending from the bottomor closed end of the compliant member. In another embodiment, apertures240 may be formed through the bottom or closed end of compliant member230. Otherwise, compliant member 230 may be generally configuredsimilarly to compliant member 30 as described above. Particularly, FIG.24 shows a side cross-sectional view (omitting apertures 240, forclarity) including flange 236, outer lip 234, and inner lip 238 formedby body 231 of compliant member 230. Thus, summarizing, a plurality ofbearing elements 230 may be coupled to the body 212 of outer race 210 sothat each bearing surface 226 of the bearing elements 220 collectivelyform a bearing surface for a radial bearing apparatus.

Accordingly, the present invention contemplates that an inner race maybe positioned within the outer race and may include a bearing surfacedefined by a plurality of bearing elements wherein each of the bearingelements has its own bearing surface. For example, FIG. 25 shows aperspective view of an inner race 260 including a plurality of bearingelements 280 positioned generally within recesses 262. Generally,bearing elements 280 may each include a bearing surface configured tocorrespond with the bearing surface of each of bearing elements 220.More specifically, FIG. 26 shows a perspective view of bearing element280 including a bearing surface 288 configured as a substantially convexsurface. In one embodiment, bearing surface 288 may comprise a portionof a substantially cylindrical surface. Further, bearing element 280includes a chamfer 287 formed on table 278, wherein table 278 is bondedto a substrate 276, which may include a chamber 279. Thus, it may beappreciated that bearing elements 280 may be coupled to the body 261 ofinner race 260 to form an inner race assembly. In further detail, FIG.27 shows a partial exploded, assembly view of inner race 260 including abearing element 280 positioned proximate to its associated recess 262.Bearing element 280 may be positioned generally within recess 262 andcoupled to the body 261 of inner race 260. For instance, bearing element280 may be adhesively bonded, brazed, welded, fastened, or otherwiseaffixed to the body 261 of inner race 260 as known in the art. Thus,inner race 260 and outer race 210 may be configured so that the bearingsurfaces (collectively defined by the plurality of bearing elements 280and the plurality of bearing elements 220) may at least partiallycontact one another. FIG. 28 shows a perspective view of a radialbearing apparatus 300 including inner race 260 positioned generallywithin outer race 210. As explained above, at least one bearing element220, 280 may be preloaded (i.e., against one another, respectively)during the assembly of radial bearing apparatus 300. Such aconfiguration may provide a radial bearing apparatus that withstandsvibrations as well as variations in the relative position of inner raceand outer race without sustaining damage. It should be understood (asexplained above with respect to the terms “rotor” and “stator”) thatinner race 260 and outer race 210 may be described as a rotor and astator, or vice versa, depending on how the inner race 260 and the outerrace 210 are configured to move relative to one another. Of course, sucha radial bearing apparatus may be included within a mechanical system.For instance, so-called “roller cone” rotary drill bits may benefit froma radial bearing apparatus contemplated by the present invention. Morespecifically, it may be appreciated that an inner race may be mounted oraffixed to a spindle of a roller cone and an outer race may be affixedto an inner bore formed within a cone and that such an outer race andinner race may be assembled to form a radial bearing apparatus. Such aradial bearing apparatus may be advantageous because of its ability towithstand relatively high temperatures and its wear resistance.Accordingly, it is contemplated that a radial bearing apparatus may becooled by a drilling fluid (i.e., a drilling mud) used to carry cuttingsfrom a leading end of a bore hole upward to the surface of asubterranean formation, as known in the art.

As mentioned above, the bearing apparatuses disclosed above may beincorporated into a mechanical system. For example, FIG. 29 shows aperspective view of a subterranean drilling system 410 incorporating athrust bearing apparatus according to the present invention. Inparticular, as known in the art, a rotary drill bit 430 may be rotatedby downhole drilling motor assembly 412. Downhole drilling motorassembly 412 may be located at the end of a series of pipe sectionscomprising a drill string. The housing 414 of downhole drilling motorassembly 412 remains stationary as rotary drill bit 430 rotates. Infurther detail, output shaft 420 of downhole drilling motor assembly 412may be coupled to rotary drill bit 430 and drilling fluid (i.e.,drilling mud) may cause torque to be applied to the output shaft 420 andto rotary drill bit 430. Rotary drill bit 430 is shown as a so-called“roller cone” type bit including roller cones 432, but may be a fixedcutter (e.g., a drill bit including polycrystalline diamond cuttingelements or compacts) or any other rotary drill bit or drilling tool(e.g., a reamer, reamer wing, impregnated diamond drill bit, core bit,etc.) as known in the art, without limitation. As shown in FIG. 29, arotor 416 and a stator 418 (i.e., a thrust bearing apparatus) may beoperably assembled to downhole drilling motor assembly 412, as known inthe art.

In one embodiment, a bearing apparatus may include polycrystallinediamond inserts or compacts defining a plurality of surfaces that moverelative to one another. Such bearing apparatuses may encompassso-called thrust bearings, radial bearings, or other bearing apparatusesincluding bearing surfaces that move in relation to one another, withoutlimitation. More particularly, the present invention relates to astructure for supporting at least one bearing element including anarcuate bearing surface (e.g., convex, concave, substantiallycylindrical, substantially spherical, etc.), wherein a bevel or chamferis formed about at least a portion of a periphery of the bearingsurface.

One aspect of the present invention relates generally to bearingapparatuses including an inner race and an outer race wherein the innerrace includes a plurality of bearing elements collectively defining abearing surface and wherein the outer race includes a plurality ofbearing elements collectively defining another bearing surface. Suchbearing elements may comprise a superhard material, such as, forexample, polycrystalline diamond. According to one aspect of the presentinvention, a bearing element may include a chamfer or other geometrythat removes or diminishes a sharp edge or corner at a periphery of abearing surface of a bearing element. Such a configuration may provide arelatively robust bearing element for use in a bearing apparatus.

Generally, a bearing element may include a superhard table or regionwhich forms a bearing surface. In one embodiment, such a bearing surfacemay be arcuate (substantially conical, substantially cylindrical,substantially spherical, concave, convex, etc.). Further, the presentinvention contemplates that at least one bearing element (of the innerrace, outer race, or both the inner race and the outer race) may includea chamfer formed about at least a portion of a periphery of the bearingsurface. Such an embodiment may provide a beneficial bearing surfaceconfiguration.

For example, in one embodiment, a bearing element may include a concavesuperhard bearing surface, wherein a chamfer is formed about at least aportion of the periphery of the arcuate, superhard bearing surface. Forexample, FIG. 30 shows a perspective view of a bearing element 510including a superhard table 520 (e.g., comprising polycrystallinediamond, cubic boron nitride, silicon carbide, etc.) formed upon asubstrate 524. In one particular embodiment, superhard table 520 maycomprise polycrystalline diamond. In another embodiment, at least aportion of superhard table 520 may comprise a silicon carbide anddiamond composite material as described in U.S. Pat. No. 7,060,641.Optionally, a chamfer 529 may be formed on a lower edge region of thesubstrate 524. In addition, as shown in FIG. 30, superhard table 520forms bearing surface 526. As shown in FIG. 30, bearing surface 526 maybe concave. In one embodiment, bearing surface 526 may be substantiallycylindrical (i.e., forming at least a portion of a substantiallycylindrical surface). Bearing surface 526 may be configured for contactwith one or more complementary shaped bearing surfaces. The presentinvention contemplates that a chamfer 527 may be formed adjacent to atleast a portion of a periphery of bearing surface 526. Explainingfurther, chamfer 527 may be formed between bearing surface 526 and sidesurface 522 of superhard table 520. Particularly, in one embodiment andas shown in FIG. 30, a chamfer 527 may be formed about substantially theentire periphery of bearing surface 526. Explaining further, FIG. 31shows a top elevation view of bearing element 510 (i.e., toward bearingsurface 526). As shown in FIG. 31, chamfer 527 surrounds bearing surface526. Put another way, chamfer 527 may be substantially continuous aboutthe periphery of bearing surface 526. Such a configuration may inhibitdamage to the bearing element 510 in response to contact with acomplementary shaped bearing surface.

Generally, the present invention contemplates that one or more chamferedregions may be formed adjacent (or about) a periphery of a bearingsurface of a bearing element. For instance, in another embodiment, achamfer may be formed about only a selected portion of a periphery of abearing surface of a bearing element. Particularly, FIG. 32 shows aperspective view of a bearing element 512 generally configured asdescribed above with respect to bearing element 510. Particularly,bearing element 512 may include a superhard table 520 forming a concavebearing surface 526. As shown in FIG. 32, bearing surface 526 may beconcave. In one embodiment, bearing surface 526 may comprise a portionof a substantially cylindrical surface. Further, chamfer 527 may beformed about at least a portion of a periphery of bearing surface 526.In further detail, FIG. 33 shows a top elevation view of bearing element512, wherein two separate chamfers 527 (or chamfered regions) are formedabout selected portions of the periphery of bearing surface 526. Thus,as shown in FIG. 33, chamfers 527 may be only formed about a selectedportion of a periphery of bearing surface 526. Chamfers 527 may besubstantially identical, substantially symmetric, or may differ from oneanother, without limitation. Optionally, substantially planar surfaces528 may be formed by superhard table 520. Also, substrate 524 mayoptionally include a chamfer 529, as shown at FIG. 32.

As discussed above, a bearing element may include an arcuate bearingsurface configured for contact with a complementary shaped arcuatebearing surface. As one of ordinary skill in the art will appreciate, inone example, bearing elements each including a concave bearing surfaceand bearing elements each including a convex bearing surface may beconfigured for contacting one another. As one of ordinary skill in theart will appreciate, a generally concave bearing surface of one or morebearing elements may be configured for contact with a generally convexbearing surface of one or more different bearing elements. Embodimentsof bearing elements including a concave bearing surface are discussedhereinabove.

Relative to a bearing element including a convex bearing surface, forexample, FIG. 34 shows a perspective view of one embodiment of a bearingelement 514 including a superhard table 520 (e.g., comprisingpolycrystalline diamond, cubic boron nitride, silicon carbide, etc.)formed upon a substrate 524, wherein the superhard table 520 forms aconvex bearing surface 536. In one embodiment, convex bearing surface536 may be substantially cylindrical (i.e., may form a portion of asubstantially cylindrical surface). Further, the present inventioncontemplates that a chamfer 527 may be formed adjacent to at least aportion of a periphery of bearing surface 536. Accordingly, chamfer 527may be formed between bearing surface 536 and side surface 522 ofsuperhard table 520. In one embodiment and as shown in FIG. 34, achamfer 527 may be formed about substantially the entire periphery ofbearing surface 536. FIG. 35 shows a top elevation view of bearingelement 514 (i.e., as if viewed toward bearing surface 536). As shown inFIG. 35, chamfer 527 surrounds bearing surface 536. Put another way,chamfer 527 may be substantially continuous about the periphery ofbearing surface 536. Such a configuration may inhibit damage to thebearing element 514 in response to contact with a complementary shapedbearing surface

In another embodiment, at least one chamfer (or chamfered region) may beformed about only a selected portion of a periphery of a bearing surfaceof a bearing element. For example, FIG. 36 shows a perspective view of abearing element 516 generally configured as described above with respectto bearing element 510. Particularly, FIG. 36 shows a perspective viewof a bearing element 516 including a superhard table 520 (e.g.,comprising polycrystalline diamond, cubic boron nitride, siliconcarbide, etc.) formed upon a substrate 524, wherein the superhard table520 forms a bearing surface 536. As shown in FIG. 36, bearing surface536 may be convex. In one embodiment, bearing surface 536 may comprise aportion of a substantially cylindrical surface. As shown in FIG. 36,chamfer 527 may be formed about at least a portion of a periphery ofbearing surface 536. In further detail, FIG. 37 shows a top elevationview of bearing element 516, wherein two separate chamfers 527 areformed about selected portions of the periphery of bearing surface 536.Chamfers 527 may be substantially identical, substantially symmetric, ormay differ from one another, without limitation.

Another aspect of the present invention relates to methods of forming abearing element including an arcuate surface. FIGS. 38 and 39 showschematic diagrams of different methods of forming a bearing elementincluding an arcuate surface and a chamfer about at least a portion of aperiphery of a bearing surface of the bearing element. FIGS. 40-42B showvarious features of an exemplary superhard compact (i.e., a superhardtable bonded to a substrate) at selected stages of process actionsdepicted in FIGS. 38 and 39. Thus, FIGS. 38-42B illustrate exemplarydetails of bearing elements at intermediate stages of manufacturerelating to methods according to the present invention.

More specifically, FIG. 38 shows a schematic diagram including actions(not necessarily in temporal order) comprising a method 600 for forminga bearing element including an arcuate surface and a chamfer about atleast a portion of a periphery of a bearing surface of the bearingelement. As shown in FIG. 38 in action 620, a superhard table may beprovided. In one embodiment, a superhard compact (i.e., a bearingelement) comprising a superhard table bonded to a substrate (e.g., apolycrystalline diamond compact) may be provided. Explaining further,FIG. 40 shows a perspective view of bearing element 508 comprising asuperhard table (e.g., polycrystalline diamond, etc.) bonded to asubstrate 524 (e.g., cobalt cemented tungsten carbide). As shown in FIG.40, superhard table 520 includes a substantially planar upper surface507 and a side surface 522. As mentioned above, superhard table 520 maybe formed upon substrate 524 by way of an ultra-high pressure,ultra-high temperature process. Subsequent to sintering superhard table520, substantially planar upper surface 507 may be formed by lapping,grinding, electro-discharge machining, and/or polishing. Optionally, asshown in FIG. 40, both superhard table 520 and substrate 524 may besubstantially cylindrical. Such a configuration may be formed bycenterless grinding or any other suitable process. In other embodiments,superhard table 520 and substrate may be oblong, elliptical, elongated,non-cylindrical, or otherwise shaped. As a further optional feature, achamfer 529 may be formed upon a lower edge of substrate 524.

Referring now to FIG. 38, method 600 may also include action 630, whichcomprises forming a chamfer upon the superhard table. Thus, as shown inFIG. 41, a chamfer 527 may be formed between side surface 522 and uppersurface 507 of superhard table 520, about a selected portion of aperiphery of upper surface 507, without limitation. Chamfer 527 may beformed by grinding, lapping, electro-discharge machining, combinationsof the foregoing, or by any suitable method or process, withoutlimitation. Explaining further, FIG. 42A shows a side cross-sectionalview of the bearing element 509 (relative to longitudinal axis 511), asshown in FIG. 41. As shown in FIG. 42A, a chamfer 527 may be formedbetween upper surface 507 and side surface 522 at a selected angle θ.Further, chamfer 527 may exhibit a selected width C_(w), as shown inFIG. 39. In one embodiment, a thickness T of superhard table 520 may beabout 0.075 inches and chamfer 527 may be formed at an angle θ of about45°, and chamfer 527 may exhibit a width C_(w) of about 0.040 inches.More generally, in another embodiment, chamfer 527 may be formed at anangle of between 5° and about 85° and may exhibit a width C_(w) ofbetween about 0.010 inches and about 0.100 inches, without limitation.One of ordinary skill in the art will understand that, in oneembodiment, chamfer 527 may be formed in such a configuration that sidesurface 522 is completely removed from at least a portion of superhardtable 520.

Referring now to FIG. 38, method 600 may further include action 640,which comprises forming an arcuate bearing surface upon the superhardtable, wherein the chamfer is adjacent at least a portion of theperiphery of the arcuate bearing surface. Thus, bearing element 509(FIGS. 41 and 42A) may be machined or otherwise modified to form abearing element including an arcuate bearing surface. For example,bearing element 509 (FIGS. 41 and 42A) may be machined or otherwisemodified to form a bearing element according to any embodiment shown inFIGS. 30-37. More specifically, by way of example, an arcuate bearingsurface may be formed upon superhard table 520 of bearing element 509 bywire electro-discharge machining (wire EDM), plunge electro-dischargemachining (plunge EDM), grinding, lapping, combinations of theforegoing, or by any other suitable method or combination of methods,without limitation. As discussed below, in one embodiment, a pluralityof bearing elements, at least one including a chamfer may be affixed toa race and then an arcuate bearing surface may be formed upon each ofthe plurality of bearing elements. Such a configuration may provide easein manufacturing and may be relatively accurate in terms of machiningtolerances.

FIG. 39 shows a schematic diagram of another embodiment of a method 602for forming a bearing element including an arcuate surface and a chamferabout at least a portion of a periphery of a bearing surface of thebearing element. Action 620 includes providing a superhard table. By wayof example, in one embodiment, as shown in FIGS. 41 and 42A, a superhardtable 520 may be formed upon a substrate 524. In a further actiondepicted in FIG. 39, method 602 may also comprise action 642, whichcomprises forming an arcuate bearing surface upon the superhard table.As discussed above, an arcuate bearing surface may be formed uponsuperhard table 520 of bearing element 509 by wire electro-dischargemachining (wire EDM), plunge electro-discharge machining (plunge EDM),grinding, lapping, combinations of the foregoing, or by any othersuitable method or combination of methods, without limitation. Forexample, bearing element 509 (FIGS. 41 and 42A) may be machined orotherwise processed to form a bearing element according to anyembodiment shown in FIGS. 30-37. Further, method 602 may include action642, which comprises forming a chamfer about at least a portion of thearcuate bearing surface. Geometrical features of a superhard table(e.g., chamfer, arcuate bearing surface, etc.) may be formed bygrinding, lapping, electro-discharge machining, combinations of theforegoing, features formed upon sintering of the superhard material, orby any suitable method or process, without limitation.

Thus, summarizing, one of ordinary skill in the art will appreciate thata chamfer may be formed, by way of example only, prior to forming anarcuate bearing surface, subsequent to forming an arcuate bearingsurface, or intermittently or contemporaneously with forming an arcuatebearing surface, without limitation. One of ordinary skill in the artwill also appreciate that if a substantially planar upper surface isformed upon a superhard table, subsequent formation of an arcuatesurface upon the superhard table may completely remove the substantiallyplanar surface or a portion of the substantially planar surface mayremain. Further, forming a chamfer and/or an arcuate bearing surface mayoccur subsequent to mounting or affixing a bearing element to a race, asdescribed hereinbelow. Such variations are contemplated by the presentinvention, without limitation.

Furthermore, the present invention contemplates that forming othergeometries about a periphery of an arcuate bearing surface may beadvantageous. For example, a radius extending between a side surface ofa diamond table about at least a portion of an arcuate bearing surfacemay provide clearance and inhibit damage to the bearing element. Forexample, FIG. 42B shows a schematic, side cross-sectional view of abearing element 505 including a radius 544 extending between uppersurface 507 and side surface 522. Radius 544 may exhibit a selected sizeand position, without limitation. Of course, multiple chamfers, tapers,rounded features, radiuses, or combinations or the foregoing may beemployed to at least partially remove an otherwise “sharp” corner orintersection between a side surface of a diamond table and an arcuatesurface of a bearing element, without limitation.

A further aspect of the present invention relates to bearing apparatusesincluding at least one bearing element according to the presentinvention. For example, FIG. 43 shows a perspective view of an outerrace 710 comprising body 712, which defines a plurality of recesses 714each configured for accepting a bearing element (e.g., shown as bearingelement 509, as described hereinabove with respect to FIGS. 41 and 42A)positioned generally therein. For example, a plurality of bearingelements 509 may be adhesively bonded, brazed, welded, fastened,mechanically affixed, or otherwise affixed to the body 712 of outer race710 by any suitable method. As shown in FIG. 43, body 712 of outer race710 may be configured in a generally ring-shaped (e.g., substantiallycylindrical ring, substantially conical ring, etc.) configuration andmay define an aperture within which an inner race may be positioned. Infurther detail, subsequent to affixing a plurality of bearing elements509 within recesses 714, respectively, arcuate bearing surfaces may beformed upon each superhard table of each bearing element 509. Forexample, each bearing element may be affixed to body 712 of outer race710 within a respective recess 714 and then a machining process may beperformed upon bearing elements 509 to form an arcuate bearing surfaceon each of bearing elements 509. Generally, as discussed above, anarcuate bearing surface may be formed by grinding, lapping,electro-discharge machining, combinations of the foregoing, featuresformed upon sintering of the superhard material, or by any suitablemethod or process, without limitation. In one embodiment, a wireelectro-discharge machining operation may be performed by traversing awire along a substantially cylindrical path within the outer race toform a respective portion of a substantially cylindrical surface uponeach bearing surface of each bearing element 509. One of ordinary skillin the art will understand that it may be, for ease of manufacturing andfor improved tolerances, beneficial to form an arcuate bearing surfaceupon each of bearing elements 509 after affixation to the outer race710. Further, it may be beneficial to form a concave (e.g.,substantially cylindrical) bearing surface upon each of bearing elements509. In other embodiments, depending on the orientation andconfiguration of the plurality of bearing elements, a bearing surface ofeach bearing element affixed to the outer race 710 may be concave,convex, or otherwise configured, without limitation.

One of ordinary skill in the art will also understand that an arcuatebearing surface may be formed on at least one bearing element prior toaffixation to body 712 of outer race 710. Such a configuration mayprovide certain advantages in manufacturing flow and ease. FIG. 44 showsa perspective view of outer race 710 including a plurality of, forexample, bearing elements 512 each including a concave bearing surface,each bearing element respectively positioned within recesses 714. Inanother embodiment, bearing elements 510 (FIGS. 30 and 31) may beemployed. As discussed above, bearing elements 512 may be formed priorto affixation to body 712 or may be formed after, for example, bearingelements 509 are affixed to body 712 of outer race 710, withoutlimitation. One of ordinary skill in the art will understand thatrecesses 714 and bearing elements 512 may be configured (e.g., sized,spaced, etc.) to provide bearing surfaces configured for interactionwith complementary shaped bearing surfaces of a plurality of bearingelements affixed to an inner race.

For example, FIG. 45 shows a partial exploded assembly view of innerrace 750 including one bearing element 509 generally aligned with recess724. Each of recesses 724 may be configured to retain a bearing element509 positioned therein. For example, bearing element 509 may beadhesively bonded, brazed, welded, fastened, mechanically affixed, orotherwise affixed to the body 752 of inner race 750 generally within arecess 724. Recesses 724 may be circumferentially spaced about the outerdiameter of inner race 750. Thus, summarizing, a plurality of bearingelements 509 may be coupled to the body 752 of inner race 750 so thateach bearing surface of the bearing elements 509 form a collectivebearing surface for a radial bearing apparatus. In one embodiment, sucha collective bearing surface may be substantially cylindrical orsubstantially conical. As discussed above, an arcuate bearing surfacemay be formed upon each of bearing elements 509 after affixation to theinner race 750. An arcuate bearing surface may be formed by grinding,lapping, electro-discharge machining, combinations of the foregoing,features formed upon sintering of the superhard material, or by anysuitable method or process, without limitation. In one embodiment, awire electro-discharge machining operation may be performed bytraversing a wire along a substantially cylindrical path about the innerrace to form a respective portion of a substantially cylindrical surfaceupon each bearing surface of each bearing element 509.

One of ordinary skill in the art will also understand that an arcuatebearing surface may be formed on at least one bearing element prior toaffixation to body 752 of inner race 750, if desired. Further, it may bebeneficial to form a convex (e.g., substantially cylindrical) bearingsurface upon each of bearing elements 509 affixed to inner race 750. Inother embodiments, depending on the orientation and configuration of theplurality of bearing elements, a bearing surface may be concave, convex,or otherwise configured, without limitation.

FIG. 46 shows a perspective view of inner race 750 including a pluralityof, for example, bearing elements 514 each including a convex bearingsurface, each bearing element 514 respectively positioned withinrecesses 724. In another embodiment, bearing elements 516 (FIGS. 36 and37) may be employed. As discussed above, bearing elements 514 may beformed prior to affixation to body 752 or may be formed from bearingelements 509 affixed to body 752 of inner race 750, without limitation.One of ordinary skill in the art will understand that recesses 724 andbearing elements 514 may be configured (e.g., sized, spaced, etc.) toprovide bearing surfaces configured for interaction with complementaryshaped bearing surfaces of a plurality of bearing elements affixed to anouter race.

Accordingly, the present invention contemplates that an inner race maybe positioned within the outer race and may include a bearing surfacedefined by a plurality of bearing elements, wherein each of the bearingelements has its own bearing surface. For example, FIG. 47 shows aperspective view of a radial bearing apparatus 780 including inner race750 positioned generally within outer race 710. Outer race 710 includesa plurality of bearing elements affixed thereto and an inner race 750includes a plurality of bearing elements affixed thereto, wherein theinner race 750 is positioned generally within the outer race 710. Thus,inner race 750 and outer race 710 may be configured so that the bearingsurfaces (collectively defined by the respective plurality of bearingelements affixed to the inner race 750 and the respective plurality ofbearing elements affixed to the outer race 710) may at least partiallycontact one another.

The present invention contemplates that although the bearing apparatusdiscussed above includes a plurality of bearing elements each includinga chamfer, the present invention is not so limited. Rather, the presentinvention contemplates that an inner race and an outer race may beassembled to form a bearing apparatus wherein at least one bearingelement of either the inner race or the outer race includes a chamferformed about at least a portion of a periphery of its arcuate bearingsurface.

Of course, such a radial bearing apparatus may be included within amechanical system. For instance, so-called “roller cone” rotary drillbits may benefit from a radial bearing apparatus contemplated by thepresent invention. More specifically, it may be appreciated that aninner race may be mounted or affixed to a spindle of a roller cone andan outer race may be affixed to an inner bore formed within a cone andthat such an outer race and inner race may be assembled to form a radialbearing apparatus. Such a radial bearing apparatus may be advantageousbecause of its ability to withstand relatively high temperatures and itswear resistance. For example, the present invention contemplates that aroller cone rotary drill bit as disclosed in U.S. Pat. No. 4,738,322 toHall, et al., the disclosure of which is incorporated herein, in itsentirety, by this reference may include at least one superhard bearingelement or a radial bearing apparatus encompassed by the presentinvention. For example, FIG. 48 shows a perspective view of asubterranean drilling system 801 incorporating a radial bearingapparatus according to the present invention. More specifically, rotarydrill bit 814 is shown as a so-called “roller cone” type bit includingroller cones 812. Further, roller cones 812 may comprise a radialbearing assembly according to the present invention wherein an innerrace is positioned adjacent to a spindle and an outer race is positionedadjacent to a surface of a roller cone 812.

As mentioned above, the bearing apparatuses disclosed above may beincorporated into any suitable mechanical system. Any other suitablerotary drill bit or drilling tool may include a radial bearing apparatusaccording to the present invention, without limitation.

Further, in another example, a radial bearing according to the presentinvention may be included within a motor or turbine. For example, thepresent invention contemplates that a roller cone rotary drill bit asdisclosed in U.S. Pat. Nos. 4,764,036, 4,410,054, and 4,560,014, thedisclosure of each of which is incorporated herein, in its entirety, bythis reference may include at least one superhard bearing element or aradial bearing apparatus encompassed by the present invention.Generally, such a downhole drilling motor assembly may be located at theend of a series of pipe sections comprising a drill string. The housingof downhole drilling motor assembly may remain stationary as a rotarydrill bit coupled thereto rotates. Thus, an output shaft of a downholedrilling motor assembly may be coupled to a rotary drill bit anddrilling fluid (i.e., drilling mud) may cause torque to be applied tothe output shaft to cause a rotary drill bit to rotate. Thus, such adownhole drilling motor or turbine assembly may include one or moreradial bearing apparatuses. Although the apparatuses and systemsdescribed above have been discussed in the context of subterraneandrilling equipment and applications, it should be understood that suchapparatuses and systems are not limited to such use and could be usedwithin a bearing apparatus or system for varied applications, ifdesired, without limitation. Thus, such apparatuses and systems are notlimited to use with subterranean drilling systems and may be used withvarious other mechanical systems, without limitation.

While certain embodiments and details have been included herein forpurposes of illustrating aspects of the instant disclosure, it will beapparent to those skilled in the art that various changes in thesystems, apparatuses, and methods disclosed herein may be made withoutdeparting from the scope of the instant disclosure, which is defined, inpart, in the appended claims. The words “including” and “having,” asused herein including the claims, shall have the same meaning as theword “comprising.”

1-20. (canceled)
 21. A bearing apparatus comprising: a first body havinga first plurality of recesses formed therein; a first plurality ofbearing elements, each bearing element having an individual bearingsurface, wherein the first plurality of individual bearing surfacesdefine a first collective bearing surface, wherein each of the firstplurality of bearing elements is at least partially disposed within anassociated recess of the first plurality of recesses, and wherein atleast one bearing element of the first plurality of bearing elementsincludes a superhard table and a chamfer extending at least partiallyaround the individual bearing surface of the at least one bearingelement; at least one compliant member associated with the at least onebearing element, the at least one compliant member being configured toenable displacement of the at least bearing element relative to thefirst body in at least one direction.
 22. The bearing apparatus of claim21, wherein each of the first plurality of bearing elements includes asuperhard table and a chamfer between a sidewall and the individualbearing surface of the at least one bearing element, and wherein the atleast one compliant member includes a plurality of compliant members,each of the plurality of compliant members being at least partiallydisposed in an associated one of the first plurality of recesses andconfigured to enable displacement of an associated one of the firstplurality of bearing elements relative to the body.
 23. The bearingapparatus of claim 21, wherein the at least one compliant membercomprises a biasing element.
 24. The bearing apparatus of claim 23,wherein the biasing element includes a wave spring washer, a curvedspring washer, or a Belleville spring washer.
 25. The bearing apparatusof claim 21, wherein the first body is substantially ring-shaped. 26.The bearing apparatus of claim 21, further comprising a second bodyhaving a surface for engagement with the first collective bearingsurface.
 27. The bearing apparatus of claim 21, further comprising: asecond body having a second plurality of recesses formed therein; asecond plurality of bearing elements, each bearing element of the secondplurality having an individual bearing surface, wherein the plurality ofindividual bearing surfaces of the second plurality of bearing elementsdefine a second collective bearing surface configured for engagementwith the first collective bearing surface, wherein each of the secondplurality of bearing elements is at least partially disposed within anassociated recess of the plurality of recesses of the second body, andwherein at least one bearing element of the second plurality of bearingelements includes a superhard table and a chamfer formed in thesuperhard table extending at least partially around the individualbearing surface; at least one additional compliant member associatedwith the at least one bearing element of the second plurality of bearingelements, the at least one additional compliant member being configuredto enable displacement of the at least bearing element of the secondplurality of bearing elements relative to the second body in at leastone direction.
 28. The bearing apparatus of claim 27, wherein the secondbody is substantially ring-shaped.
 29. The bearing apparatus of claim28, wherein the individual bearing surface of the at least one bearingelement of the first plurality of bearing elements includes an arcuatebearing surface, and wherein the individual bearing surface of the atleast one bearing element of the second plurality of bearing elementsincludes an arcuate bearing surface.
 29. The bearing apparatus of claim21, wherein the bearing apparatus is configured as a thrust bearing. 30.The bearing apparatus of claim 21, wherein the individual bearingsurface of the at least one bearing element of the first plurality ofbearing elements includes an arcuate bearing surface.
 31. The bearingapparatus of claim 30, wherein the chamfer extends only partially aroundthe arcuate bearing surface.
 32. The bearing apparatus of claim 31,wherein the at least one chamfer exhibits a variation in width as itextends along a periphery of the arcuate bearing surface.
 33. Thebearing apparatus of claim 21, wherein each of the individual bearingsurfaces includes an arcuate bearing surface.
 34. The bearing apparatusof claim 33, wherein each arcuate bearing surface includes a concavesurface.
 35. The bearing apparatus of claim 33, wherein each arcuatebearing surface includes a convex surface.